Working to protect steelhead while maintaining flood protection for Santa Barbara County

Winter 2014

Seventeen flood control debris-basin dams stretch across southern California’s Santa Barbara County. They are designed to store large sediment flows, and most were constructed originally to retain debris from the surrounding landscape burned in wildland fires between the 1960s and 1990s. Today, the dams continue to capture large sediment deposits. However, many of the areas have recovered from the fires and debris-basin dams no long operate as once intended. Further, the use of debris-basin dams to trap sediment loads resulting from wildland fires is no longer common practice. While these structures continue to protect the communities of Santa Barbara, Carpenteria, Goleta, Santa Maria, and Guadalupe, they also impact Southern California steelhead, a federally endangered species endemic to this region.

Each year, the Santa Barbara Flood Control District (District) removes debris and sediment from debris-basins, provides structural upgrades, and clears 60 county drainages of vegetation that may obstruct water flow. Though this maintenance is crucial, some activities undermine the natural processes that support the creation of spawning, rearing, and migration habitat for steelhead. For example, the riparian vegetation and large wood that is often cleared from streams is actually critical to maintaining suitable stream temperatures for steelhead. Additionally, the debris-basin dams block steelhead from accessing high quality spawning and rearing habitat upstream.

Because steelhead depend on free, unobstructed passage, as well as cool water and healthy habitat, the District is making changes to its stream maintenance program. The District plans to modify dams that inhibit fish passage, protect habitat by implementing guidelines that limit the removal of riparian vegetation, and provide passage at new or repaired grade-control structures to ensure steelhead can migrate to and from the ocean.

The proposed modifications are required as part of the U.S. Army Corps of Engineers’ authorization of Santa Barbara County’s Stream Maintenance Program. NOAA Fisheries found that the program’s status-quo operations disrupt the migration of fish and impair their habitats. Working with the other agencies, NOAA Fisheries identified a series of corrective actions that will soon be implemented to benefit steelhead.

Southern California Coast steelhead once returned in significant numbers—annual estimates range from 32,000 to 46,000 fish. Numbers declined sharply to less than 500 adult fish returning each year, leading to its federal listing as an endangered species in 1997. NOAA Fisheries adopted a plan to recover Southern California Coast steelhead in 2012, identifying fish passage and protection of riparian habitats as essential to the species’ recovery. Efforts by the Santa Barbara County Flood Control District to enhance fish passage and minimize the removal of riparian vegetation will contribute to the recovery of these fish while ensuring the maintenance of the flood-control structures will continue to protect local communities throughout the county.